Vertical Split-Ring Resonators for Plasmon Coupling, Sensing and Metasurface

Din Ping Tsai Department of Physics, National Taiwan University, Taipei, Taiwan Research Center for Applied Sciences, Academia Sinica, Taipei, Taiwan Pin Chieh Wu Department of Physics, National Taiwan University, Taipei, Taiwan Wei-Lun Hsu Department of Physics, National Taiwan University, Taipei, Taiwan Wei Ting Chen Department of Physics, National Taiwan University, Taipei, Taiwan Yao-Wei Huang Department of Physics, National Taiwan University, Taipei, Taiwan Chun Yen Liao Department of Physics, National Taiwan University, Taipei, Taiwan Wei-Yi Tsai Department of Physics, National Taiwan University, Taipei, Taiwan Ai Qun Liu School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore, Singapore Nikolay Zheludev Optoelectronics Research Centre and Centre for Photonics Metamaterials, University of Southampton, Southampton, UK Greg Sun Department of Engineering, University of Massachusetts Boston, Boston, USA

Plasmonic metamaterials composed of artificial structures in subwavelength scale exhibit many unconventional properties for light manipulation, and it is also very promising for photonic devices, high-sensitivity optical sensor etc. Split-ring resonator (SRR), one kind of building block of metamaterials, has attracted wide attentions due to the resonance excitation of electric and magnetic dipolar response. Here, the fundamental plasmon properties and potential applications in novel three dimensional vertical split-ring resonators (VSRRs) are designed and investigated.

The resonant properties arose from the electric and magnetic interactions between the VSRR and light are theoretically and experimentally studied. Tuning the configuration of VSRR unit cells is able to generate various novel coupling phenomena in VSRRs, such as plasmon hybridization [Fig. 1(a)] and Fano resonance [Fig. 1(b)] [1]. The magnetic resonance plays a key role in plasmon coupling in VSRRs. The VSRR-based refractive-index sensor will be demonstrated, as shown in Figs. 1(c). Due to the unique structural configuration, the enhanced plasmon fields localized in VSRR gaps can be lifted off from the dielectric substrate, allowing for the increase of sensing volume and enhancing the sensitivity [2]. We perform a VSRR based metasurface for light manipulation in optical communication frequency, as shown in 1(d) as well. By varying the prong heights, the 2π phase modulation can be achieved in VSRR for the design of metasurface. Because the phase shift is changed via the upright configuration rather than the one parallel to the substrate, it can be used for high areal density integration of metal nanostructures and opto-electronic devices.

Fig. 1. Schematic diagrams for VSRR based (a) plasmon coupling, (b) Fano resonance, (c) nanoplasmonic sensor and (d) metasurface

References

[1] P. C. Wu, W. T. Chen, K.-Y. Yang, C. T. Hsiao, G. Sun, A. Q. N. I. Zheludev and D. P. Tsai, “Magnetic plasmon induced transparency in three dimensional metamolecules,” Nanophotonics 1, 131-138 (2012).

[2] P. C. Wu, G. Sun, W. T. Chen, K.-Y. Yang, Y.-W. Huang, Y.-H. Chen, H. L. Huang, W.-L. Hsu, H.-P. Chiang and D. P. Tsai, “Vertical split-ring resonator based nanoplasmonic sensor,” Appl. Phy. Lett. 105, 033105 (2014).

dptsai@phys.ntu.edu.tw